“Let’s Hang On!” is a song composed by Bob Crewe, Sandy Linzer, and Denny Randell that was popularized by The Four Seasons in 1965. The single reached the number three position in the Billboard Hot 100 singles chart, the group’s highest placement since “Rag Doll” hit the top spot in July 1964.
This was the last Four Seasons hit to feature bass singer/bassist Nick Massi. The same month “Let’s Hang On!” was released, Massi left the group and was temporarily replaced by the band’s arranger Charles Calello before Joe Long came in as Massi’s full-time replacement.
The popularity of “Let’s Hang On!” has been attributed to the inclusion of several devices into the recording: a two-line introduction (sung by lead singer Frankie Valli), the use of two fuzz guitars (one guitarist playing low notes, another playing high notes on a fuzz bass), a chorus loaded with hooks and sung in falsetto, and backing vocals giving counterpoint with Valli’s lead vocal. It re-established the group’s presence in the Top Ten (of the Hot 100) as The Four Seasons were in a flurry of activity, recording albums both as The Four Seasons and as supporting musicians for Valli’s rekindled “solo” career. In the UK, the song was a No.4 hit for the group.
The single’s B-side, “On Broadway Tonight”, was the theme of a CBS-TV variety series (1964–1965) hosted by Rudy Vallee.
In 1966 Jan & Dean recorded “Let’s Hang On!” for their 1966 Filet Of Soul album.
In 1980, the song was covered by British doo-wop band Darts who took it to Number 11 in the UK singles chart. This was the band’s last UK top 40 single.
In 1981, the song was revived by Barry Manilow who hit number six on the Billboard Adult Contemporary chart and number 32 on the Hot 100. The single climbed to number 12 in the United Kingdom and was certified silver,  while peaking at number 4 in Australia, number 16 in Germany and number 8 in Ireland.